This invention relates to welding apparatus and, particularly, a drive feed roller assembly for advancing a consumable filler wire to a nozzle of the welding apparatus to produce a weld on a work piece.
The form and quality of the weld in consumable electrode arc welding depends on a large number of variables, one of which is proper feeding of the filler wire to the nozzle or welding area of the apparatus. Some consumable wire feeding systems feed the wire at a rate proportional to arc voltage, usually at a constant rate. Other systems feed the consumable wire intermittently, but in most apparatus, feed rollers are provided for engaging the consumable wire to move the wire from a supply reel thereof longitudinally to the welding area. The consumable wire must be fed generally in a straight line without causing bends or kinks which could jam the apparatus as well as reduce the quality of the weld itself.
During usage, the feed rollers become worn or can be damaged whereupon they must be replaced in order to maintain a high quality feeding system of the filler wire to the weld. One form of feed roller heretofore utilized comprises a single feed roller (with a backup roller) and which has a plurality of circular grooves disposed generally parallel and axially of the feed roller. The single roller with multiple grooves is held at various set positions on a rotatable drive shaft, for instance, so as to position one of the grooves of the roller for proper engagement with the filler wire in one of the grooves. As a groove becomes worn, the axial disposition of the feed roller would be changed on the drive shaft so as to dispose another groove in position for proper engagement with the filler wire. One disadvantage with such a unitary, multiple grooved roller is that should the roller be damaged, it would have to be replaced not withstanding the fact that one or more of the multiple grooves had not even been used during operation. In addition, separate spacer members had to be provided on the drive shaft, adding cost to the apparatus, so as to maintain different axial positions of the multiple groove roller on the drive shaft.
The present invention is directed to providing a new and improved feed roller assembly for use in a consumable wire welding apparatus, without the disadvantages of the prior art as described above.
More particularly, the drive feed roller assembly of the present invention is designed for use in a welding apparatus which utilizes a consumable wire to produce a weld on a work piece, as the feed roller assembly advances the consumable filler wire to a welding area or nozzle. The apparatus includes a rotatable drive shaft on which the feed roller assembly is mounted generally concentric with the axis of rotation of the drive shaft for rotation therewith. In a form of the invention shown herein, the drive shaft has an enlarged portion defining a shoulder against which the roller assembly abuts at one end of the assembly, and a holding means in the form of a collar positioned about the drive shaft for bearing against the opposite end of the assembly, with means for releasably clamping the collar to the drive shaft.
The feed roller assembly includes a plurality of individual roller segments or wafers mounted axially on the drive shaft and each individual roller segment has a generally concentric peripheral circular groove for engaging and advancing the consumable filler wire to the weld area or nozzle of the welding apparatus. Each individual roller segment or wafer is removable from the drive shaft for selectively interchanging the roller segments in different side-by-side arrangements on the drive shaft to permit placement of any one of the roller segments in position for engaging the filler wire. An end one of the side-by-side roller segments abuts against the shoulder defined by the enlarged portion of the drive shaft and the opposite end roller segment is engaged by the holding means or clamping collar.
With a feed roller assembly of the character described and shown herein, comprising a plurality of individual roller segments or wafers, should one of the roller segments become damaged, only that segment need be replaced resulting in cost savings. In addition, should the groove on one of the roller segments become worn through usage, the plural roller segments need only be rearranged in a different side-by-side relationship so as to present the groove on another roller segment in position to properly engage the consumable wire. Thus, no spacer members need be employed on the drive shaft, due to the simple shifting and rearrangement of the roller segments.
In the form of the invention shown herein, the peripheral grooves of the roller segments are generally channel-shaped with smooth side wall portions and a bottom wall portion which is provided with a friction surface, such as a knurled surface, engageable with the filler wire.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.